--- /dev/null
+/*
+ * art_render_gradient.c: Gradient image source for modular rendering.
+ *
+ * Libart_LGPL - library of basic graphic primitives
+ * Copyright (C) 2000 Raph Levien
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ *
+ * Authors: Raph Levien <raph@acm.org>
+ * Alexander Larsson <alla@lysator.liu.se>
+ */
+
+#include "config.h"
+#include "art_render_gradient.h"
+
+#include <math.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <assert.h>
+
+/* Hack to find out how to define alloca on different platforms.
+ * Modified version of glib/galloca.h.
+ */
+
+#ifdef __GNUC__
+/* GCC does the right thing */
+# undef alloca
+# define alloca(size) __builtin_alloca (size)
+#elif defined (HAVE_ALLOCA_H)
+/* a native and working alloca.h is there */
+# include <alloca.h>
+#else /* !__GNUC__ && !HAVE_ALLOCA_H */
+# ifdef _MSC_VER
+# include <malloc.h>
+# define alloca _alloca
+# else /* !_MSC_VER */
+# ifdef _AIX
+ #pragma alloca
+# else /* !_AIX */
+# ifndef alloca /* predefined by HP cc +Olibcalls */
+char *alloca ();
+# endif /* !alloca */
+# endif /* !_AIX */
+# endif /* !_MSC_VER */
+#endif /* !__GNUC__ && !HAVE_ALLOCA_H */
+
+#undef DEBUG_SPEW
+
+typedef struct _ArtImageSourceGradLin ArtImageSourceGradLin;
+typedef struct _ArtImageSourceGradRad ArtImageSourceGradRad;
+
+/* The stops will be copied right after this structure */
+struct _ArtImageSourceGradLin {
+ ArtImageSource super;
+ ArtGradientLinear gradient;
+ ArtGradientStop stops[1];
+};
+
+/* The stops will be copied right after this structure */
+struct _ArtImageSourceGradRad {
+ ArtImageSource super;
+ ArtGradientRadial gradient;
+ double a;
+ ArtGradientStop stops[1];
+};
+
+#define EPSILON 1e-6
+
+#ifndef MAX
+#define MAX(a, b) (((a) > (b)) ? (a) : (b))
+#endif /* MAX */
+
+#ifndef MIN
+#define MIN(a, b) (((a) < (b)) ? (a) : (b))
+#endif /* MIN */
+
+static void
+art_rgba_gradient_run (art_u8 *buf,
+ art_u8 *color1,
+ art_u8 *color2,
+ int len)
+{
+ int i;
+ int r, g, b, a;
+ int dr, dg, db, da;
+
+#ifdef DEBUG_SPEW
+ printf ("gradient run from %3d %3d %3d %3d to %3d %3d %3d %3d in %d pixels\n",
+ color1[0], color1[1], color1[2], color1[3],
+ color2[0], color2[1], color2[2], color2[3],
+ len);
+#endif
+
+ r = (color1[0] << 16) + 0x8000;
+ g = (color1[1] << 16) + 0x8000;
+ b = (color1[2] << 16) + 0x8000;
+ a = (color1[3] << 16) + 0x8000;
+ dr = ((color2[0] - color1[0]) << 16) / len;
+ dg = ((color2[1] - color1[1]) << 16) / len;
+ db = ((color2[2] - color1[2]) << 16) / len;
+ da = ((color2[3] - color1[3]) << 16) / len;
+
+ for (i = 0; i < len; i++)
+ {
+ *buf++ = (r>>16);
+ *buf++ = (g>>16);
+ *buf++ = (b>>16);
+ *buf++ = (a>>16);
+
+ r += dr;
+ g += dg;
+ b += db;
+ a += da;
+ }
+}
+
+static void
+calc_color_at (ArtGradientStop *stops,
+ int n_stops,
+ ArtGradientSpread spread,
+ double offset,
+ double offset_fraction,
+ int favor_start,
+ int ix,
+ art_u8 *color)
+{
+ double off0, off1;
+ int j;
+
+ if (spread == ART_GRADIENT_PAD)
+ {
+ if (offset < 0.0)
+ {
+ color[0] = ART_PIX_8_FROM_MAX (stops[0].color[0]);
+ color[1] = ART_PIX_8_FROM_MAX (stops[0].color[1]);
+ color[2] = ART_PIX_8_FROM_MAX (stops[0].color[2]);
+ color[3] = ART_PIX_8_FROM_MAX (stops[0].color[3]);
+ return;
+ }
+ if (offset >= 1.0)
+ {
+ color[0] = ART_PIX_8_FROM_MAX (stops[n_stops-1].color[0]);
+ color[1] = ART_PIX_8_FROM_MAX (stops[n_stops-1].color[1]);
+ color[2] = ART_PIX_8_FROM_MAX (stops[n_stops-1].color[2]);
+ color[3] = ART_PIX_8_FROM_MAX (stops[n_stops-1].color[3]);
+ return;
+ }
+ }
+
+ if (ix > 0 && ix < n_stops)
+ {
+ off0 = stops[ix - 1].offset;
+ off1 = stops[ix].offset;
+ if (fabs (off1 - off0) > EPSILON)
+ {
+ double interp;
+ double o;
+ o = offset_fraction;
+
+ if ((fabs (o) < EPSILON) && (!favor_start))
+ o = 1.0;
+ else if ((fabs (o-1.0) < EPSILON) && (favor_start))
+ o = 0.0;
+
+ /*
+ if (offset_fraction == 0.0 && !favor_start)
+ offset_fraction = 1.0;
+ */
+
+ interp = (o - off0) / (off1 - off0);
+ for (j = 0; j < 4; j++)
+ {
+ int z0, z1;
+ int z;
+ z0 = stops[ix - 1].color[j];
+ z1 = stops[ix].color[j];
+ z = floor (z0 + (z1 - z0) * interp + 0.5);
+ color[j] = ART_PIX_8_FROM_MAX (z);
+ }
+ return;
+ }
+ /* If offsets are too close to safely do the division, just
+ pick the ix color. */
+ color[0] = ART_PIX_8_FROM_MAX (stops[ix].color[0]);
+ color[1] = ART_PIX_8_FROM_MAX (stops[ix].color[1]);
+ color[2] = ART_PIX_8_FROM_MAX (stops[ix].color[2]);
+ color[3] = ART_PIX_8_FROM_MAX (stops[ix].color[3]);
+ return;
+ }
+
+ printf ("WARNING! bad ix %d in calc_color_at() [internal error]\n", ix);
+ assert (0);
+}
+
+static void
+art_render_gradient_linear_render_8 (ArtRenderCallback *self,
+ ArtRender *render,
+ art_u8 *dest, int y)
+{
+ ArtImageSourceGradLin *z = (ArtImageSourceGradLin *)self;
+ const ArtGradientLinear *gradient = &(z->gradient);
+ int i;
+ int width = render->x1 - render->x0;
+ int len;
+ double offset, d_offset;
+ double offset_fraction;
+ int next_stop;
+ int ix;
+ art_u8 color1[4], color2[4];
+ int n_stops = gradient->n_stops;
+ int extra_stops;
+ ArtGradientStop *stops = gradient->stops;
+ ArtGradientStop *tmp_stops;
+ art_u8 *bufp = render->image_buf;
+ ArtGradientSpread spread = gradient->spread;
+
+#ifdef DEBUG_SPEW
+ printf ("x1: %d, x2: %d, y: %d\n", render->x0, render->x1, y);
+ printf ("spread: %d, stops:", gradient->spread);
+ for (i=0;i<n_stops;i++)
+ {
+ printf ("%f, ", gradient->stops[i].offset);
+ }
+ printf ("\n");
+ printf ("a: %f, b: %f, c: %f\n", gradient->a, gradient->b, gradient->c);
+#endif
+
+ offset = render->x0 * gradient->a + y * gradient->b + gradient->c;
+ d_offset = gradient->a;
+
+ /* We need to force the gradient to extend the whole 0..1 segment,
+ because the rest of the code doesn't handle partial gradients
+ correctly */
+ if ((gradient->stops[0].offset > EPSILON /* == 0.0 */) ||
+ (gradient->stops[n_stops-1].offset < (1.0 - EPSILON)))
+ {
+ extra_stops = 0;
+ tmp_stops = stops = alloca (sizeof (ArtGradientStop) * (n_stops + 2));
+ if (gradient->stops[0].offset > EPSILON /* 0.0 */)
+ {
+ memcpy (tmp_stops, gradient->stops, sizeof (ArtGradientStop));
+ tmp_stops[0].offset = 0.0;
+ tmp_stops += 1;
+ extra_stops++;
+ }
+ memcpy (tmp_stops, gradient->stops, sizeof (ArtGradientStop) * n_stops);
+ if (gradient->stops[n_stops-1].offset < (1.0 - EPSILON))
+ {
+ tmp_stops += n_stops;
+ memcpy (tmp_stops, &gradient->stops[n_stops-1], sizeof (ArtGradientStop));
+ tmp_stops[0].offset = 1.0;
+ extra_stops++;
+ }
+ n_stops += extra_stops;
+
+
+#ifdef DEBUG_SPEW
+ printf ("start/stop modified stops:");
+ for (i=0;i<n_stops;i++)
+ {
+ printf ("%f, ", stops[i].offset);
+ }
+ printf ("\n");
+#endif
+
+ }
+
+ if (spread == ART_GRADIENT_REFLECT)
+ {
+ tmp_stops = stops;
+ stops = alloca (sizeof (ArtGradientStop) * n_stops * 2);
+ memcpy (stops, tmp_stops, sizeof (ArtGradientStop) * n_stops);
+
+ for (i = 0; i< n_stops; i++)
+ {
+ stops[n_stops * 2 - 1 - i].offset = (1.0 - stops[i].offset / 2.0);
+ memcpy (stops[n_stops * 2 - 1 - i].color, stops[i].color, sizeof (stops[i].color));
+ stops[i].offset = stops[i].offset / 2.0;
+ }
+
+ spread = ART_GRADIENT_REPEAT;
+ offset = offset / 2.0;
+ d_offset = d_offset / 2.0;
+
+ n_stops = 2 * n_stops;
+
+#ifdef DEBUG_SPEW
+ printf ("reflect modified stops:");
+ for (i=0;i<n_stops;i++)
+ {
+ printf ("%f, ", stops[i].offset);
+ }
+ printf ("\n");
+#endif
+ }
+
+ offset_fraction = offset - floor (offset);
+#ifdef DEBUG_SPEW
+ printf ("inital offset: %f, fraction: %f d_offset: %f\n", offset, offset_fraction, d_offset);
+#endif
+ /* ix is selected so that offset_fraction is
+ stops[ix-1] <= offset_fraction <= stops[ix]
+ If offset_fraction is equal to one of the edges, ix
+ is selected so the the section of the line extending
+ in the same direction as d_offset is between ix-1 and ix.
+ */
+ for (ix = 0; ix < n_stops; ix++)
+ if (stops[ix].offset > offset_fraction ||
+ (d_offset < 0.0 && fabs (stops[ix].offset - offset_fraction) < EPSILON))
+ break;
+ if (ix == 0)
+ ix = n_stops - 1;
+ else if (ix == n_stops)
+ ix = n_stops - 1;
+
+#ifdef DEBUG_SPEW
+ printf ("Initial ix: %d\n", ix);
+#endif
+
+ assert (ix > 0);
+ assert (ix < n_stops);
+ assert ((stops[ix-1].offset <= offset_fraction + EPSILON) ||
+ ((stops[ix].offset > (1.0 - EPSILON)) && (offset_fraction < EPSILON /* == 0.0*/)));
+ assert (offset_fraction <= stops[ix].offset);
+ /* FIXME: These asserts may be broken, it is for now
+ safer to not use them. Should be fixed!
+ See bug #121850
+ assert ((offset_fraction != stops[ix-1].offset) ||
+ (d_offset >= 0.0));
+ assert ((offset_fraction != stops[ix].offset) ||
+ (d_offset <= 0.0));
+ */
+
+ while (width > 0)
+ {
+#ifdef DEBUG_SPEW
+ printf ("ix: %d\n", ix);
+ printf ("start offset: %f\n", offset);
+#endif
+ calc_color_at (stops, n_stops,
+ spread,
+ offset,
+ offset_fraction,
+ (d_offset > -EPSILON),
+ ix,
+ color1);
+
+ if (d_offset > 0)
+ next_stop = ix;
+ else
+ next_stop = ix-1;
+
+#ifdef DEBUG_SPEW
+ printf ("next_stop: %d\n", next_stop);
+#endif
+ if (fabs (d_offset) > EPSILON)
+ {
+ double o;
+ o = offset_fraction;
+
+ if ((fabs (o) <= EPSILON) && (ix == n_stops - 1))
+ o = 1.0;
+ else if ((fabs (o-1.0) <= EPSILON) && (ix == 1))
+ o = 0.0;
+
+#ifdef DEBUG_SPEW
+ printf ("o: %f\n", o);
+#endif
+ len = (int)floor (fabs ((stops[next_stop].offset - o) / d_offset)) + 1;
+ len = MAX (len, 0);
+ len = MIN (len, width);
+ }
+ else
+ {
+ len = width;
+ }
+#ifdef DEBUG_SPEW
+ printf ("len: %d\n", len);
+#endif
+ if (len > 0)
+ {
+ offset = offset + (len-1) * d_offset;
+ offset_fraction = offset - floor (offset);
+#ifdef DEBUG_SPEW
+ printf ("end offset: %f, fraction: %f\n", offset, offset_fraction);
+#endif
+ calc_color_at (stops, n_stops,
+ spread,
+ offset,
+ offset_fraction,
+ (d_offset < EPSILON),
+ ix,
+ color2);
+
+ art_rgba_gradient_run (bufp,
+ color1,
+ color2,
+ len);
+ offset += d_offset;
+ offset_fraction = offset - floor (offset);
+ }
+
+ if (d_offset > 0)
+ {
+ do
+ {
+ ix++;
+ if (ix == n_stops)
+ ix = 1;
+ /* Note: offset_fraction can actually be one here on x86 machines that
+ does calculations with extended precision, but later rounds to 64bit.
+ This happens if the 80bit offset_fraction is larger than the
+ largest 64bit double that is less than one.
+ */
+ }
+ while (!((stops[ix-1].offset <= offset_fraction &&
+ offset_fraction < stops[ix].offset) ||
+ (ix == 1 && offset_fraction > (1.0 - EPSILON))));
+ }
+ else
+ {
+ do
+ {
+ ix--;
+ if (ix == 0)
+ ix = n_stops - 1;
+ }
+ while (!((stops[ix-1].offset < offset_fraction &&
+ offset_fraction <= stops[ix].offset) ||
+ (ix == n_stops - 1 && offset_fraction < EPSILON /* == 0.0*/)));
+ }
+
+ bufp += 4*len;
+ width -= len;
+ }
+}
+
+
+/**
+ * art_render_gradient_setpix: Set a gradient pixel.
+ * @render: The render object.
+ * @dst: Pointer to destination (where to store pixel).
+ * @n_stops: Number of stops in @stops.
+ * @stops: The stops for the gradient.
+ * @offset: The offset.
+ *
+ * @n_stops must be > 0.
+ *
+ * Sets a gradient pixel, storing it at @dst.
+ **/
+static void
+art_render_gradient_setpix (ArtRender *render,
+ art_u8 *dst,
+ int n_stops, ArtGradientStop *stops,
+ double offset)
+{
+ int ix;
+ int j;
+ double off0, off1;
+ int n_ch = render->n_chan + 1;
+
+ for (ix = 0; ix < n_stops; ix++)
+ if (stops[ix].offset > offset)
+ break;
+ /* stops[ix - 1].offset < offset < stops[ix].offset */
+ if (ix > 0 && ix < n_stops)
+ {
+ off0 = stops[ix - 1].offset;
+ off1 = stops[ix].offset;
+ if (fabs (off1 - off0) > EPSILON)
+ {
+ double interp;
+
+ interp = (offset - off0) / (off1 - off0);
+ for (j = 0; j < n_ch; j++)
+ {
+ int z0, z1;
+ int z;
+ z0 = stops[ix - 1].color[j];
+ z1 = stops[ix].color[j];
+ z = floor (z0 + (z1 - z0) * interp + 0.5);
+ if (render->buf_depth == 8)
+ dst[j] = ART_PIX_8_FROM_MAX (z);
+ else /* (render->buf_depth == 16) */
+ ((art_u16 *)dst)[j] = z;
+ }
+ return;
+ }
+ }
+ else if (ix == n_stops)
+ ix--;
+
+ for (j = 0; j < n_ch; j++)
+ {
+ int z;
+ z = stops[ix].color[j];
+ if (render->buf_depth == 8)
+ dst[j] = ART_PIX_8_FROM_MAX (z);
+ else /* (render->buf_depth == 16) */
+ ((art_u16 *)dst)[j] = z;
+ }
+}
+
+static void
+art_render_gradient_linear_done (ArtRenderCallback *self, ArtRender *render)
+{
+ art_free (self);
+}
+
+static void
+art_render_gradient_linear_render (ArtRenderCallback *self, ArtRender *render,
+ art_u8 *dest, int y)
+{
+ ArtImageSourceGradLin *z = (ArtImageSourceGradLin *)self;
+ const ArtGradientLinear *gradient = &(z->gradient);
+ int pixstride = (render->n_chan + 1) * (render->depth >> 3);
+ int x;
+ int width = render->x1 - render->x0;
+ double offset, d_offset;
+ double actual_offset;
+ int n_stops = gradient->n_stops;
+ ArtGradientStop *stops = gradient->stops;
+ art_u8 *bufp = render->image_buf;
+ ArtGradientSpread spread = gradient->spread;
+
+ offset = render->x0 * gradient->a + y * gradient->b + gradient->c;
+ d_offset = gradient->a;
+
+ for (x = 0; x < width; x++)
+ {
+ if (spread == ART_GRADIENT_PAD)
+ actual_offset = offset;
+ else if (spread == ART_GRADIENT_REPEAT)
+ actual_offset = offset - floor (offset);
+ else /* (spread == ART_GRADIENT_REFLECT) */
+ {
+ double tmp;
+
+ tmp = offset - 2 * floor (0.5 * offset);
+ actual_offset = tmp > 1 ? 2 - tmp : tmp;
+ }
+ art_render_gradient_setpix (render, bufp, n_stops, stops, actual_offset);
+ offset += d_offset;
+ bufp += pixstride;
+ }
+}
+
+static void
+art_render_gradient_linear_negotiate (ArtImageSource *self, ArtRender *render,
+ ArtImageSourceFlags *p_flags,
+ int *p_buf_depth, ArtAlphaType *p_alpha)
+{
+ if (render->depth == 8 &&
+ render->n_chan == 3)
+ {
+ self->super.render = art_render_gradient_linear_render_8;
+ *p_flags = 0;
+ *p_buf_depth = 8;
+ *p_alpha = ART_ALPHA_PREMUL;
+ return;
+ }
+
+ self->super.render = art_render_gradient_linear_render;
+ *p_flags = 0;
+ *p_buf_depth = render->depth;
+ *p_alpha = ART_ALPHA_PREMUL;
+}
+
+/**
+ * art_render_gradient_linear: Add a linear gradient image source.
+ * @render: The render object.
+ * @gradient: The linear gradient.
+ *
+ * Adds the linear gradient @gradient as the image source for rendering
+ * in the render object @render.
+ **/
+void
+art_render_gradient_linear (ArtRender *render,
+ const ArtGradientLinear *gradient,
+ ArtFilterLevel level)
+{
+ ArtImageSourceGradLin *image_source = art_alloc (sizeof (ArtImageSourceGradLin) +
+ sizeof (ArtGradientStop) * (gradient->n_stops - 1));
+
+ image_source->super.super.render = NULL;
+ image_source->super.super.done = art_render_gradient_linear_done;
+ image_source->super.negotiate = art_render_gradient_linear_negotiate;
+
+ /* copy the gradient into the structure */
+ image_source->gradient = *gradient;
+ image_source->gradient.stops = image_source->stops;
+ memcpy (image_source->gradient.stops, gradient->stops, sizeof (ArtGradientStop) * gradient->n_stops);
+
+ art_render_add_image_source (render, &image_source->super);
+}
+
+static void
+art_render_gradient_radial_done (ArtRenderCallback *self, ArtRender *render)
+{
+ art_free (self);
+}
+
+static void
+art_render_gradient_radial_render (ArtRenderCallback *self, ArtRender *render,
+ art_u8 *dest, int y)
+{
+ ArtImageSourceGradRad *z = (ArtImageSourceGradRad *)self;
+ const ArtGradientRadial *gradient = &(z->gradient);
+ int pixstride = (render->n_chan + 1) * (render->depth >> 3);
+ int x;
+ int x0 = render->x0;
+ int width = render->x1 - x0;
+ int n_stops = gradient->n_stops;
+ ArtGradientStop *stops = gradient->stops;
+ art_u8 *bufp = render->image_buf;
+ double fx = gradient->fx;
+ double fy = gradient->fy;
+ double dx, dy;
+ double *affine = gradient->affine;
+ double aff0 = affine[0];
+ double aff1 = affine[1];
+ const double a = z->a;
+ const double arecip = 1.0 / a;
+ double b, db;
+ double c, dc, ddc;
+ double b_a, db_a;
+ double rad, drad, ddrad;
+
+ dx = x0 * aff0 + y * affine[2] + affine[4] - fx;
+ dy = x0 * aff1 + y * affine[3] + affine[5] - fy;
+ b = dx * fx + dy * fy;
+ db = aff0 * fx + aff1 * fy;
+ c = dx * dx + dy * dy;
+ dc = 2 * aff0 * dx + aff0 * aff0 + 2 * aff1 * dy + aff1 * aff1;
+ ddc = 2 * aff0 * aff0 + 2 * aff1 * aff1;
+
+ b_a = b * arecip;
+ db_a = db * arecip;
+
+ rad = b_a * b_a + c * arecip;
+ drad = 2 * b_a * db_a + db_a * db_a + dc * arecip;
+ ddrad = 2 * db_a * db_a + ddc * arecip;
+
+ for (x = 0; x < width; x++)
+ {
+ double z;
+
+ if (rad > 0)
+ z = b_a + sqrt (rad);
+ else
+ z = b_a;
+ art_render_gradient_setpix (render, bufp, n_stops, stops, z);
+ bufp += pixstride;
+ b_a += db_a;
+ rad += drad;
+ drad += ddrad;
+ }
+}
+
+static void
+art_render_gradient_radial_negotiate (ArtImageSource *self, ArtRender *render,
+ ArtImageSourceFlags *p_flags,
+ int *p_buf_depth, ArtAlphaType *p_alpha)
+{
+ self->super.render = art_render_gradient_radial_render;
+ *p_flags = 0;
+ *p_buf_depth = render->depth;
+ *p_alpha = ART_ALPHA_PREMUL;
+}
+
+/**
+ * art_render_gradient_radial: Add a radial gradient image source.
+ * @render: The render object.
+ * @gradient: The radial gradient.
+ *
+ * Adds the radial gradient @gradient as the image source for rendering
+ * in the render object @render.
+ **/
+void
+art_render_gradient_radial (ArtRender *render,
+ const ArtGradientRadial *gradient,
+ ArtFilterLevel level)
+{
+ ArtImageSourceGradRad *image_source = art_alloc (sizeof (ArtImageSourceGradRad) +
+ sizeof (ArtGradientStop) * (gradient->n_stops - 1));
+ double fx = gradient->fx;
+ double fy = gradient->fy;
+
+ image_source->super.super.render = NULL;
+ image_source->super.super.done = art_render_gradient_radial_done;
+ image_source->super.negotiate = art_render_gradient_radial_negotiate;
+
+ /* copy the gradient into the structure */
+ image_source->gradient = *gradient;
+ image_source->gradient.stops = image_source->stops;
+ memcpy (image_source->gradient.stops, gradient->stops, sizeof (ArtGradientStop) * gradient->n_stops);
+
+ /* todo: sanitycheck fx, fy? */
+ image_source->a = 1 - fx * fx - fy * fy;
+
+ art_render_add_image_source (render, &image_source->super);
+}
git.asbjorn.biz / swftools.git / blobdiff